1. Field of the Invention
The present invention relates to a reset circuit for power-on and power-off, and more particularly, to a reset circuit for power-on and power-off used in source drivers of an LCD (liquid crystal display) panel.
2. Description of the Related Art
Liquid crystal display (LCD) has the features being light, thin, small volume, low radiation, and saving power. These features allow the space used in the office or at home to decrease, as well as help reduce the eye fatigue due to staring at the LCD screen for too long. Therefore, in the planar display apparatus, LCD has the potential to replace the conventional CRT (cathode ray tube). FIG. 1 shows an LCD module used in an LCD monitor/TV. The LCD module includes a panel 2, a source driver unit 3, a gate driver unit 4 and a timing controller 5. The timing controller 5 controls the timing and sequence of display of a pixel of an image by sending control signals to the source driver unit 3 and the gate driver unit 4. Source drivers in the source driver unit 3 control the writing of pixel values into pixels (not shown) in the panel 2. Gate drivers in the gate driver unit 4 control the on/off operation of MOS transistors associated with the pixels by signals GS. When power-on and power-off of the LCD monitor/TV, the power supply and the signals from the timing controller 5 to the source driver unit 3 are usually unstable or in an unknown state. Thus, the output signals SS of the source driver unit 3 are in unknown states, resulting in a noise-like image on the panel 2.
To provide high quality image display and reduce the consumers' complaints, it is necessary to eliminate the noise-like image on the panel when power-on and power-off.